1. Field of the Invention
The present invention relates to a wireless multicasting service method using a relayed transmission scheme for effectively providing multicasting services without modifying a conventional network structure in the Internet environment where wired or wireless networks are integrated.
This work was supported by the IT R&D program of MIC/IITA[2006-P10-40, System and method for providing multicast service in a mobile network by using relayed multicast]
2. Description of the Related Art
As a communication technology has been advanced, a user is allowed to easily access the Internet through a wired or a wireless link. Due to such an easy Internet access, the demands of users have been advanced from text based services to multimedia data services. The multimedia data service basically requires high capacity data transmission. Especially, a wireless multimedia group communication service, for example, a mobile IPTV, requires high capacity multimedia data to transmit in a comparatively narrower wireless environment. When a plurality of receivers are present at the same mobile network, it needs to protect the network resources from being wasted by high capacity multimedia.
A wireless multicasting service was introduced as a mechanism to effectively support the above described services. FIG. 1 is a diagram illustrating a system for providing a multicasting service in a wired and wireless integrated Internet environment according to the related art.
Referring to FIG. 1, the system includes a multicast data sender 100 for transmitting data, a plurality of mobile nodes 500-1 and 500-2 for receiving data transmitted from the sender 100, mobile networks 30-1 and 30-2 for enabling the mobile nodes MN 500-1 and 500-2 to transmit and receive data through a wireless link, and a multicast network 20 having a plurality of multicast routers 21, 22, 23, and 24 between the sender 100 and the mobile networks 30-1 and 30-2.
A multicast tress that is a data transmission path among the multicast routers is set in the multicast network 30. When the sender 100 transmits predetermined data to the mobile nodes 500-1 and 500-2 joining to the multicast routers 21, 22, 23, and 24 through an internet group management protocol (IGMP), the data is transferred to the predetermined mobile nodes 500-1 and 500-2 through the corresponding multicast tree and the mobile network. Herein, when the mobile nodes 500-1 and 500-2 move to a new mobile network, the multicast tree in the wired network is required to be newly formed.
In order to provide multicasting services to a wired and wireless integrated Internet environment, a multicast network using multicast routers is required to be built by modifying the conventional network structure.
If a predetermined mobile node frequently moves to various locations in a wireless environment, the mobile node frequently performs handovers. According to the frequent handover, the multicast trees must be continuously modified.